Areas of Interest

I've written a (IMO) nice ruleset that I am playtesting with a few people in my immediate surroundings. I've received some requests from people outside my gaming circle that also would like to help playtesting but I'm a bit puzzled how to get such a thing started?

Do you guys just make a PDF of your rules and bits and just send them over to anyone who wants? Don't I risk that someone just copies it and goes to a publisher with it? (worst case scenario here :P) Or am I just a bit too nervous about it?